Compound substance for electric insulators



UNITED STATES PATENT OFFICE.

THOMAS J. MAYALL, OF READING, MASSACHUSETTS.

COMPOUND SUBSTANCE FOR ELECTRIC INSULATORS.

SPECIFICATION forming part of Letters Patent No. 243,782, dated July 5, 1881.

Application filed May 7, 1881.

To all whom it may concern:

Be it known that I, THOMAS J. MAYALL, of Reading, in the county of Middlesex and State of Massachusetts, have invented a new and useful Improvementin a Compound Substance from which Electric Insulators in any form may be made, of which the following is a specification.

My invention relates to the compound of materials of which the insulating substance is made and the manner of combining and treating them to produce it.

The object of this invention is to produce a substance which shall be, as nearly as possible, a perfect non-conductor of electricity, which can be molded or cut, sawed, turned, or carved in any desired form, and which will combine strength and durability, and at a mode atecost; and it consists in making a compound mass consisting of rubber, graphite, and sulphide or sulphuret of antimony in proportions, by weight, as follows:- to one pound of rubber one-quarter of a pound to two pounds of graphite and one-half a pound to two pounds of sulphide or sulphuretof antimony. These are thoroughly commingled and blended together into a plastic mass, and cured by heat to the consistency of hard rubber, so called.

Insulating articles may be molded from the compound mass before it is cured, and then cured; or masses of the compound may be cured, and desired insulating articles cut-from it and worked into the shape required, and finished and polished as metals and hard wood are finished and polished.

To cure this compound I heat it in an oven, as hard rubber is cured, or in any practicable manner, for about one hour at 232 Fahrenheit, one-half hour at about 235, one-half hour (No specimens.)

at 240 one-half hour at 245 one-half hour at about 250 one-half hour at about 255, onehalf hour at about 260 one-half hour at about 265 one-half hour at about 270 one-halfhour at about 275 one-hall hour at about 280 onehalf hour at about 2859, one-half hour at about 290 one-half hour at about 295 and one hour at about 300 in all about eight hours, when it will be found to be sufficiently hard and with the most perfect insulating qualities.

From this substance I make all the parts of electrical machines and apparatus and instruments which it is necessary or desirable to have made of non-electric conducting or insulating substance, and also boxes and cases to contain such when in use, and tanks for chemicals used. It may be used instead of glass for insulators to sustain telegraph-wires on the poles.

Iron orothcr metals and substances may be coated to a considerable thickness with the plastic compound, and then heated, as before 011s. HOUGHTON H. KENNEY, Jr. 

